Metabolic Bone Disease in Tortoises – Causes and Treatments

Reptiles can fall victim to several health problems, Metabolic Bone Disease (MBD) being one of them. Tortoises also fall into this category, and there are several reasons for that.

Today, we will look into Metabolic Bone Disease to assess its triggers, symptoms, potential treatments, and the best prevention tactics available. Let’s get to it!

What is Metabolic Bone Disease (MBD)?

MBD is essentially a bone condition that affects reptiles in particular, although another group of animals can also experience it.

While the problem is mostly diet-related, several other factors can trigger it along the way. The main problem with MBD is that this disorder is typically deadly, primarily due to its multitude of effects.

The most noticeable ones include:

  • Decrease bone density – This can lead to difficulty moving and an increased risk of fractures. This issue is particularly concerning for tortoises due to the extra weight that they need to carry around. Larger tortoises are even more prone to the condition.
  • Abnormal bone growth – This is more prevalent among younger tortoises because they grow at a more accelerated rate. A juvenile tortoise with MBD can experience abnormal bone growth, consisting of curved bones, deformities, and thickened joints, leading to impaired movement, pain, and stiff walking. The severity of the symptoms varies depending on the disorder’s progression and the reptile’s susceptibility.
  • Secondary health problems – The previous 2 health issues are common occurrences, as they define the way Metabolic Bone Disease works. But what many reptile owners don’t know is that MBD is also responsible for a variety of additional health problems. These include digestive issues, increased risk of eye and skin infections, decreased immune function, and even organ damage. These extra problems make MBD deadlier than it would normally be and decrease the treatment’s effectiveness.

It’s important to note that MBD involves a lot of pain and suffering the more it advances. So, you need to find adequate treatment fast or consider euthanasia if your vet has determined that the disorder is beyond any solution.

In severe cases, MBD can even lead to extreme movement impairment and paralysis, which doesn’t spare the reptile from the relentless pain impulses.

Causes of Metabolic Bone Disease in Tortoise

Metabolic Bone Disease links to several triggers, such as:

Improper Diet

The diet is the most important part because it’s the main MBD trigger. Essentially, MBD is a nutrition-related condition, typically stemming off of improper eating. Tortoises are omnivorous reptiles with a changing diet.

To understand tortoises better from a nutritional standpoint, consider the following general facts:

  • Tortoises’ diet changes with time – Tortoises qualify as omnivorous reptiles, but they have a predominantly herbivorous diet as adults. However, juveniles consume a lot more animal protein and fat from sources like insects, worms, crustaceans, etc. This is to support their naturally higher metabolism and growth rate. As the tortoise ages, the diet will naturally steer toward more vegetarian dishes that rely on flowers, leaves, plants, dark greens, fruits, veggies, etc.
  • Diversity is a must – We constantly hear that meal diversity is a must for reptiles, but this notion is pretty subjective. A typical snake won’t mind eating the same type of prey for a long time, especially since some snakes only eat once every several weeks or even months. However, tortoises require genuine food diversity because they tend to eat daily. This means that they need a variety of foods to provide them with a well-rounded dish of vitamins, minerals, and protein.
  • The need for water-rich foods – Water-rich foods are also necessary because that’s how tortoises hydrate, to begin with. They also drink water and hydrate through their skin, based on their ecosystem’s humidity levels, but the amount of water found in their food is critical.
  • UVB radiation is necessary – Not all reptiles require UVB radiation to the same degree that tortoises do. They need a basking spot where they will spend a lot of time taking in all the UVB radiation they can get. This is to boost their metabolism and speed up the digestive process because they eat daily, so they need to digest their food relatively fast. Then there’s the issue of vitamin D synthesis, which is necessary to ensure proper calcium absorption.

Analyzing these simple facts should inform you about what ‘improper diet’ refers to. If your tortoise’s meal isn’t diverse enough, the animal doesn’t have access to UVB light, and you don’t understand your reptile’s nutritional needs, MBD is but assured.

The most common trigger of MBD is poor calcium absorption, leading to calcium deficiency, which will affect the tortoise’s skeletal system directly.

This is why some of the first symptoms of MBD have a lot to do with poor walking, lethargy, bone deformities, and joint inflammation.

Poor Husbandry and Improper Parameters

Tortoises aren’t particularly messy animals, but they still require adequate maintenance to stay healthy and strong.

We have several points to consider here:

  • General maintenance – A filthy habitat will result in your tortoise experiencing various health issues, including respiratory conditions, skin infections, parasites, bacterial infections, fungal infections, etc. All these produce multiple symptoms and side effects, including poor nutrient absorption, low metabolism, lethargy, and loss of appetite. These are almost assured to trigger MBD eventually.
  • Improper temperature – Cold temperatures are known to affect the animal’s metabolism and influence the digestive process directly. As a result, the tortoise will experience digestive problems, slowing down digestion and causing nutritional deficiency along the way.
  • Improper humidity – Tortoises require adequate humidity and easy access to a constant source of fresh and clean water. Without that, the reptile may not have sufficient water to ensure the effectiveness of the digestive system. Dehydration, even in mild forms, leads to constipation, skin conditions, and respiratory difficulties, among other things.

Fortunately, these conditions are fairly easy to circumvent with the help of a good care routine in place. In essence, you should remove food leftovers immediately after your tortoise is done eating, clean feces and urine, and clean and disinfect the reptile’s habitat as often as necessary.

The goal is to prevent bacterial and fungal formations that may attack your tortoise’s skin or respiratory system, which are bound to devolve into more life-threatening health problems.

Genetic Predisposition

Reptiles, in general, are predisposed toward experiencing calcium deficiency, but this isn’t the only problem. Some reptiles are more sensitive than others, putting them at higher risk for developing calcium deficiency and nutritional imbalances.

These specimens typically require highly-personalized diets, intense nutritional planning, dietary supplementation, and regular vet checkups.

Unfortunately, there’s nothing you can do to prevent this issue. That is, other than selecting your tortoise carefully from a reputed breeder who can provide extra information on the tortoise’s parents.

Symptoms of MBD in Tortoises

The primary symptoms of MBD may vary, depending on the triggers and the severity of the condition.

These include:

  • Abnormal shell growth – The shell occupies much of the tortoise’s body, so it’s easy to observe any unusual features that may link to MBD. Abnormal shell curvatures, various deformities, or random thickening are all signs of shell issues, most likely linked to MBD. These symptoms are worrying because their effects are not merely aesthetical. A deformed shell will also impact the tortoise’s movement.
  • Brittle shell – The severe lack of calcium leads to lower bone density, which will also affect the shell’s consistency. This makes the shell prone to damage, which can quickly turn into a life-or-death situation. The shell covers the tortoise’s internal organs, and it is part of the animal’s body. Cracks and visible shell damage lead to pain and an increased risk of infection.
  • Overall lethargy – Tortoises aren’t the most active animals on the planet, but you should be able to tell when they’re lethargic. Lethargic tortoises showcase low energy levels even during their most active hours. This is due to the stress associated with the pain and the inability to move properly. The lack of activity will contribute to the tortoise’s degrading mental state, worsening the situation fast.
  • Difficulty feeding and low appetite – MBD also affects the tortoise’s beak, which is made out of bone and keratin. A deformed beak will prevent the tortoise from eating properly, leading to nutritional imbalances and deficiencies, which will aggravate the animal’s state even further.
  • Fractures – It’s not normal for the tortoise to experience fractures in captivity, provided it lives in a safe habitat. Even if the enclosure’s layout permits falls due to a 2-story setting, that situation still won’t warrant a fracture. Tortoises are fairly resilient animals, and they don’t break bones from minor falls like that. Any sign of limping or visible fracture tells the story of MBD in more advanced phases.
  • Breathing difficulties – Breathing difficulties are common in advanced MBD due to the condition affecting the animal’s ribs and chest muscles. This causes the victim to experience trouble inflating the ribcage, leading to difficulties inhaling. The situation is even more problematic for tortoises that crawl on their ribcage for the most part and have a lot of weight to carry around.

These symptoms are common among most reptiles affected by MBD and vary in intensity, depending on the disorder’s progression.

Fortunately, you can detect them in time in most situations, allowing you to provide your pet with the necessary treatment and assistance.

Diagnosing MBD in Tortoises

If you suspect your tortoise may have experienced MBD, a timely diagnosis is necessary to begin the right treatment asap.

You can diagnose the condition by following these steps:

  • Physical examination – This is the first phase because physical symptoms are the easiest to diagnose. Look for shell deformities like abnormal shapes, bumps on the shell, abnormal limb positioning or shape, awkward walking, lethargy, signs of shell cracking, signs of fractures, etc. Every tortoise may give away various symptoms, depending on the condition’s severity and how it is affecting that specimen in particular.
  • Blood testing – Blood tests are meant to reveal the amount of calcium, phosphorus, and vitamin D (among other nutrients) present in the tortoise’s system. These can indicate abnormal parameters, allowing the professional to diagnose your tortoise’s condition accurately.
  • X-Ray – Radiographies are meant to investigate the bone structure to determine bone density and showcase any signs of cracks or fractures. That’s because small bone cracks may not be visible to the naked eye. You will only notice that your tortoise appears distressed, but you may not be able to spot any other symptoms.
  • Biopsy – If everything else fails, the vet may need to perform a shell biopsy. This is to determine the shell’s thickness, growth pattern, hardness, and overall structure.

You should consider these steps as soon as you notice any worrying symptoms that may indicate a health problem.

Remember, MBD is a fast-progressing disorder that requires early detection and treatment.

Treatment Options for MBD in Tortoises

I want to begin by saying that MBD is very difficult to treat overall and impossible to treat in its final stages. So, early treatment is absolutely paramount to help the tortoise recover safely.

The following treatments may help with that:

  • Dietary changes – Metabolic Bone Disease is essentially a dietary disorder. So, that’s where the treatment should consider during the first phase of the attack. The treatment consists of adjusting the tortoise’s diet according to what the diagnosis process has revealed. Add more calcium and vitamin D into the animal’s diet and remove as much phosphorus as possible from the meals. That’s because phosphorus neutralizes some of the calcium, which means that high-calcium food items are worthless if they also contain a lot of phosphorus.
  • Ensure adequate UVB lighting – Tortoises require adequate UVB lighting to aid with calcium absorption. This is particularly necessary for tortoises due to their higher need for vitamin D and calcium. Provide them with a serious basking spot with temperatures around 90-100 F for adequate UVB absorption.
  • Food supplements – If the situation is rather severe and requires a fast approach, calcium and vitamin D supplementation may be necessary to speed things up. This also works as a prevention method to minimize the risk of MBD in the first place.
  • Shell repair – The shell will record much of the MBD-related damage, so that’s what the treatment procedure should target, among other things. Your vet may recommend shell casts or even surgery to correct the shell damage, depending on the location of the damage and its severity.

No matter the treatment you’re going for, always keep your vet in the picture. MBD is a serious condition that can easily aggravate past the point of no return. You need all the professional assistance you can get.

Prevention Tips for MBD in Tortoises

Naturally, you want to prevent MBD rather than treat it, given the disorder’s profile and aggressivity.

Here are some steps to follow in this sense:

  • Adjust the reptile’s diet – Most tortoises have similar dietary requirements but are not identical. Some specimens prefer some food items over others, which also applies to the specimens belonging to the same species. Make sure that your tortoise has a well-rounded diet catering to its nutritional needs. Keep the focus on leafy greens, veggies, and fruits for optimal calcium and vitamin D intake and lower the amount of phosphorus. Side note: don’t overdo it with veggies and fruits. Too much sugar and fibers aren’t ideal for tortoises.
  • UVB lighting – We’ve already mentioned this approach as a treatment procedure, but it works even better as a prevention method. Tortoises should always have access to adequate UVB lighting to ensure adequate vitamin D synthesis and the best calcium absorption rate.
  • Don’t over-supplement – Too much calcium and vitamin D can actually backfire and cause a range of health problems. Always discuss the issue with your vet so you can apply the correct dietary modifications.
  • Regular monitoring – Sometimes, things can work against you and your tortoise, despite all of the preventive measures in place. If your tortoise is genetically predisposed towards developing MBD, your preventive strategies might not work as well. Older tortoises are more likely to develop MBD at some point. So, it’s essential to monitor the reptile regularly to detect the early signs of MBD. The earlier the MBD treatment, the higher the chances of recovery.


Metabolic Bone Disease is undoubtedly a ruthless disease. You can decrease its impact and treat it to some degree, but the affected tortoise may never recover in full in some cases.

If the prevention strategy has failed and the treatment doesn’t seem to work as intended, I recommend euthanasia as a better option.

Discuss this alternative with your vet, as the professional’s insight is gold in this sense.

Robert from ReptileJam

Hey, I'm Robert, and I have a true passion for reptiles that began when I was just 10 years old. My parents bought me my first pet snake as a birthday present, which sparked my interest in learning more about them. read more...